Icom IC-91A User manual

SERVICE
MANUAL
VHF/UHF FM TRANSCEIVER
S-14230HZ-C1
May. 2006
VHF/UHF DIGITAL TRANSCEIVER
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INTRODUCTION
This service manual describes the latest service information
for the IC-91A VHF/UHF FM TRANSCEIVER, IC-91AD
VHF/UHF DIGITAL TRANSCEIVER at the time of
publication.
ORDERING PARTS
Be sure to include the following four points when ordering
replacement parts:
1. 10-digit Icom parts number
2. Component name and informations
3. Equipment model name and unit name
4. Quantity required
<SAMPLE ORDER>
5030002880 LCD HLM7972-010100 IC-91A Main unit 5 pieces
8810009560 Screw PH BT M2×6 ZK IC-91A Chassis 10 pieces
Addresses are provided on the inside back cover for your
convenience.
REPAIR NOTES
1. Make sure the problem is internal before disassembling the transceiver.
2. DO NOT open the transceiver until the transceiver is disconnected from its power source.
3. DO NOT force any of the variable components. Turn them slowly and smoothly.
4. DO NOT short any circuits or electronic parts. An insulated turning tool MUST be used for all adjustments.
5. DO NOT keep power ON for a long time when the transceiver is defective.
6. DO NOT transmit power into a signal generator or a sweep generator.
7. ALWAYS connect a 30 dB to 40 dB attenuator between the transceiver and a deviation meter or spectrum analyzer when
using such test equipment.
8. READ the instructions of test equipment thoroughly before connecting equipment to the transceiver.
To upgrade quality, all electrical or mechanical parts and internal
circuits are subject to change without notice or obligation.
MODEL VERSION SYMBOL
IC-91AD U.S.A. USA
Export EXP
IC-91A
U.S.A. USA-1
Taiwan TPE
Korea KOR
Australia AUS
Export EXP-1
EXP-2
Icom, Icom Inc. and logo are registered trademarks of Icom Incorporated (Japan) in the United States, the United
Kingdom, Germany, France, Spain, Russia and/or other countries.
NEVER connect the transceiver to an AC outlet or to a DC
power supply 3.7 V. Such a connection could cause a fire or
electric hazard.
DO NOT expose the transceiver to rain, snow or any liquids.
DO NOT reverse the polarities of the power supply when
connecting the transceiver.
DO NOT apply an RF signal of more than 20 dBm (100 mW)
to the antenna connector. This could damage the trans-
ceiver's front end.
CAUTION
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TABLE OF CONTENTS
SECTION 1 SPECIFICATIONS
SECTION 2 INSIDE VIEWS
SECTION 3 DISASSEMBLY INSTRUCTIONS
SECTION 4 UT-121 UNINSTALLATION
SECTION 5 CIRCUIT DESCRIPITON
5-1 RECEIVER CIRCUITS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5-2 TRANSMITTER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
5-3 PLL CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
5-4 OTHER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
5-5 POWER SUPPLY CIRCUITS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
5-6 PORT ALLOCATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
SECTION 6 ADJUSTMENT PROCEDURES
6-1 PREPARATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
6-2 FREQUENCY AND TRANSMIT ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
SECTION 7 PARTS LIST
SECTION 8 MECHANICAL PARTS AND DISASSEMBLY
SECTION 9 SEMICONDUCTOR INFORMATION
SECTION 10 BOARD LAYOUTS
10-1 LOGIC UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
10-2 MAIN UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
10-3 RF UNIT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
10-4 UT-121 (Optional product; CODEC UNIT for IC-91AD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
10-5 VCO UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
SECTION 11 BLOCK DIAGRAM
SECTION 12 VOLTAGE DIAGRAMS
12-1 LOGIC UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-1
12-2 MAIN UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-2
12-3 RF UNIT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-3
12-4 VCO UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-4
12-5 UT-121 (Optional product; CODEC UNIT for IC-91AD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-5
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1 - 1
SECTION 1 SPECIFICATIONS
GENERAL
• Frequency coverange :
• Operating mode :FM, AM*, WFM*, DV†(*RX only)
• Memory channels : 1304 channels
(Incl. 100 scan edges and 4 call ch.)
• Frequency stability : ±2.5 ppm
(–20°C to +60°C; –4°F to 140°F)
• Tuning steps : 5‡/6.25‡/8.33‡/9‡/10/12.5/15/20/
25/30/50/100/125 and 200 kHz
• Antenna impedance : 50 Ω(SMA type)
• Power supply : 10.0–16.0 V DC for external DC
power, or specified Icom’s battery
pack
• Digital transmission speed : 4.8 kbps†
• Voice coding speed : 2.4 kbps†
• Current drain (at 7.4 V DC) :
TRANSMIT VHF High 2.1 A typ.
Low 0.8 A (approx.)
UHF High 2.2 A typ.
Low 0.8 A (approx.)
RECEIVE Stand-by 170 mA typ.
(dualwatch; FM/DV†)
Max. audio 340 mA typ.
(dualwatch; FM/DV†)
• Operating temp. range : –20°C to +60°C; –4°F to 140°F
• Dimensions
(projections not included)
: 58.4 (W) × 103 (H) × 34.2 (D) mm
2 9/32 (W) × 4 1/16 (H) × 1 11/32 (D) in
• Weight (approx.) :300 g; 10.6 oz
(antenna, BP-217 included)
TRANSMITTER
• Output power (at 7.4 V DC) : 5.0 W (High)
0.5 W (Low; aprrox.)
• Modulation system FM : Variable reactance frequency
modulation
DV†GMSK reactance frequency
modulation
• Maximum deviation : ±5.0 kHz (FM wide: approx.)
±2.5 kHz (FM narrow: approx.)
• Spurious emissions : Less than –60 dB
• Ext. mic. connector : 3-conductor 2.5 (d) mm; (
1/10′′
)/2 kΩ
RECEIVER
• Receiving system :
FM/AM/DV†Double-conversion
superheterodyne system
WFM Triple-conversion
superheterodyne system
• Intermediate frequencies :
1st A band
B band
61.65/59.25 MHz (WFM)
46.35 MHz
2nd 450 kHz/13.35 MHz (WFM)
3rd 1.95 MHz (WFM only)
• Sensitivity : (except spurious points)
• Selectivity :
FM (Wide), AM More than 50 dB
FM (Narrow), DV†More than 45 dB
WFM More than 300 kHz/–3 dB
Less than 700 kHz/–20 dB
• Spurious image rejection :
VHF More than 60 dB
UHF More than 50 dB
(IF; More than 60 dB)
• Audio output power
(at 7.4 V DC)
: More than 200 mW
(at 10% distortion with an 8 Ωload)
• Ext. speaker connector : 3-conductor 3.5 (d) mm; (
1/8′′
)/8 Ω
All stated specifications are subject to change without notice or obligation.
†Available for the IC-91AD or when UT-121 is installed into the IC-91A.
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SECTION 4 UT-121 UNINSTALLATION
4 - 1
2 screws
Unit cover
UT-121
(Top view)
Notches
Tweezers
qTurn the power OFF, and remove the battery pack.
wUnscrew 2 screws to remove the unit cover.
eInsert the tweezers into the notches of the UT-121, and remove it as shown below.
rScrew 2 screws to assemble the unit cover.
2 screws
Unit cover
RECOMMENDATION:
Critical technique is necessary for the UT-121 uninstallation, therefore, we recommend you to uninstall it at your
dealer or service center.
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1-1-32, Kamiminami, Hirano-ku, Osaka 547-0003, Japan S-14230HZ-C1
© 2006 Icom Inc.
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